Definition

1. Noun:
   • The process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. This is a vital physiological process in plants.
   • The process of giving off water vapor through the skin or mucous membranes. This refers to a form of evaporation from the bodies of humans or animals.
   • The passage of gases through fine tubes or pores due to differences in pressure or temperature. This is a more general physical process.

Usage and Examples

• Noun (Botany):
  • Transpiration helps cool the plant and is a major force in drawing water up from the roots.
  • Scientists measure the rate of transpiration to understand a plant's water needs.
• Noun (Physiology):
  • A small amount of body cooling occurs through cutaneous transpiration.
• Noun (Physics):
  • The transpiration of gases through the membrane was measured in the experiment.

Advanced Usage

• "Transpiration stream": The continuous flow of water from the roots to the leaves, driven largely by transpiration.
  • The transpiration stream transports minerals from the soil throughout the plant.
• "Transpiration pull": The suction force created by the evaporation of water from leaves that pulls water upward through the xylem.
  • Transpiration pull is a key mechanism for moving water to the tops of tall trees.

Variants and Related Words

• Transpire (verb): To occur or happen; or, to give off vapor or moisture (the original, now less common, meaning).
  • It later transpired that he had left the company. (meaning: it became known)
  • Plants transpire water vapor. (meaning: give off)
• Transpirational (adjective): Relating to transpiration.
  • The transpirational water loss was high on the hot, windy day.

Synonyms

• Evaporation (specifically for the process of a liquid turning to vapor).
• Exhalation (specifically for the physiological process of giving off vapor).
• Perspiration (specifically for the process of sweating, which is a form of transpiration in animals).

Related Phrases and Terms

• "Transpiration rate": The speed at which water is lost from a plant, typically measured per unit leaf area per unit time.
  • Wind and low humidity increase the transpiration rate.
• "Transpiration efficiency": The ratio of carbon assimilation (photosynthesis) to water loss through transpiration.
  • Drought-resistant crops often have higher transpiration efficiency.

Noun

1. the emission of water vapor from the leaves of plants
2. the process of giving off or exhaling water vapor through the skin or mucous membranes
3. the passage of gases through fine tubes because of differences in pressure or temperature